1) Technical Field
The subject invention relates to a method for manufacturing a one-piece torsional vibration damper retainer plate for operation in a torque converter.
2) Description of the Prior Art
Torsional vibration dampers are well known components in torque converters. As appreciated, torque converters operate as a fluid coupling between an output of an engine and an input of a transmission of a vehicle. Additionally however, torque converters implement torsional vibration dampers as lock-up clutches to dampen or reduce torsional vibrations generated between the engine and the transmission of the vehicle during the mechanical engagement of the lock-up clutch, or torsional vibration damper.
Specifically, torsional vibration dampers include a driven or retainer plate and a drive plate. Referring to the prior art retainer plate 100 of a conventional torsional vibration damper (not shown) detailed in FIG. 1, the retainer plate 100 includes a central plate segment 102 and an annular periphery 104 having a distal end 106. The annular periphery 104 of the retainer plate 100 extends upwardly at approximately 90xc2x0 from the central plate segment 102. As such, a generally L-shaped channel 108 is established between the central plate segment 102 and the annular periphery 104. Continuing, a plurality of compression springs 110, critical to the dampening function of the torsional vibration damper, are disposed in the generally L-shaped channel 108. To retain the spring 110 in the L-shaped channel 108, a plurality of spring support brackets 112 are mounted to the central plate segment 102. The requirement of incorporating the plurality of spring support brackets 112 to assist in retaining the springs in the generally L-shaped channel 108 is disadvantageous as will be realized further hereinbelow.
More specifically, the spring support brackets 112 include a support segment 114 and a distal retention segment 116. For support purposes, the support segment 114 of each spring support bracket 112 is rigidly mounted to the central plate segment 102 of the retainer plate 100. Further, the distal retention segment 116 of each spring support bracket 112 angularly extends toward the distal end 106 of the annular periphery 104 thereby spanning the generally L-shaped channel 108 to retain the springs in the generally L-shaped channel 108 during assembly and operation of the torsional vibration damper.
The incorporation of the spring support brackets 112 contribute additional material, additional weight, and additional costs to the retainer plate 100 of the torsional vibration damper.
A second conventional torsional vibration damper is disclosed in U.S. Pat. No. 4,903,803 (the ""803 patent) to Koshimo. The ""803 patent discloses a conventional torsional vibration damper including a driven or retainer plate and a drive plate. As with the retainer plate disclosed in FIG. 1, the retainer plate of the ""803 patent also includes a central plate segment and an annular periphery having a distal end. The annular periphery of the retainer plate in the ""803 patent is partially curled to establish a generally C-shaped channel between the central plate segment and the annular periphery. Continuing, a plurality of compression springs are disposed in the generally C-shaped channel for dampening torsional vibrations. Although the annular periphery of the retainer plate in the ""803 patent is curled to establish a generally C-shaped channel, the annular periphery is only partially curled. As such, the annular periphery of the ""803 patent is not sufficiently curled to independently retain the springs in the generally C-shaped channel, and the retainer plate of the ""803 patent only operates in conjunction with the drive plate to retain the springs.
Instead of independently retaining the springs, the ""803 patent must additionally incorporate vertical support walls stamped out of the retainer plate. The stamping of the vertical support walls adds time to the manufacture of the retainer plate. Further, the stamping of the vertical walls directly out of the retainer plate necessarily forms xe2x80x9copeningsxe2x80x9d dispersed throughout a circumference of the retainer plate thereby detracting from the overall structural integrity of the retainer plate in the ""803 patent.
Also because the annular periphery of the ""803 patent is only partially curled, the drive plate that interacts with retainer plate must include supplemental construction at an outer periphery of the drive plate to assist the retainer plate in retaining the springs during operation of the torsional vibration damper by encompassing at least a portion of a circumference of the springs. In sum, similar to retainer plate disclosed in FIG. 1, the retainer plate disclosed in the ""803 patent must additionally incorporate vertical support walls that detract from the overall structural integrity of the retainer plate, and the drive plate disclosed in the ""803 patent must additionally incorporate supplemental construction at the outer periphery which contributes additional material, additional weight, and additional costs to the drive plate of the torsional vibration damper.
Due to the inefficiencies identified in such conventional torsional vibration dampers, it is desirable to implement a method for manufacturing a driven or retainer plate that retains at least one spring without any additional components.
A method for manufacturing a one-piece torsional vibration damper retainer plate having an annular periphery curled into a generally C-shaped channel for retaining at least one spring comprises the step of disposing the spring about the annular periphery of the retainer plate. The method further comprises, and is characterized by, the step of curling the annular periphery of the retainer plate into the generally C-shaped channel to substantially surround the spring to prevent the spring from being removed from the C-shaped channel of the retainer plate during operation of the retainer plate. As appreciated, the generally C-shaped channel may retain more than one spring. That is, the annular periphery of the retainer plate may be curled into a generally C-shaped channel for retaining a plurality of springs. Continuing, the step of curling the annular periphery is further defined by first partially curling the annular periphery to receive the spring or springs and thereafter completing the curling of the annular periphery about the spring or springs. Additionally, the method incorporates the step of heat treating the retainer plate to change physical properties of the retainer plate between the step of partially curling the annular periphery and the step of completing the curling of the annular periphery.
Accordingly, the subject invention provides a method for manufacturing a driven or retainer plate having an annular periphery curled into a generally C-shaped channel that substantially surrounds at least one spring to prevent the spring from being removed from the C-shaped channel of the retainer plate during operation of the retainer plate. As a result, the retainer plate manufactured according to the subject invention independently retains the spring in the generally C-shaped channel thereby requiring less material, less weight, and less cost than the conventional retainer plates of the prior art.